Giving first person all my points and

1. Yes they are congruent. You translate AB to move it over to CD. Specifically, shift 2 units to the right.

2. No, they are not congruent. QR is longer than MN. Congruent segments must be the same length.

3. No, they are not congruent. At first glance, they seem to be congruent after translation and reflection. However, XY is longer than UV, and those legs should be the same length for a pair of congruent triangles to be possible.

4. Yes they are congruent. You translate triangle ABC to move it over to triangle DEF (shift 1 to the left, 3 down).

a = 3.14

b = 18

c = 18/5 or 3.6 or 3 3/5

step-by-step explanation: